Janez Kovač

Janez Kovač
Jožef Stefan Institute | IJS · Department of Surface Engineering

About

348
Publications
41,527
Reads
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5,424
Citations
Citations since 2016
156 Research Items
3419 Citations
20162017201820192020202120220200400600
20162017201820192020202120220200400600
20162017201820192020202120220200400600
20162017201820192020202120220200400600
Additional affiliations
March 2003 - December 2021
Jožef Stefan Institute
Position
  • Senior Researcher
Description
  • Head of Laboratory for Surface and Thin Analysis
November 1995 - February 2003
Institute of Surface Engineering and Optoelectronics
Position
  • Researcher
July 1995 - December 1999
Synchrotron Elettra, Trieste, Italy
Position
  • Researcher
Description
  • ESCA Microscopy beamline, TWINMIC beamline

Publications

Publications (348)
Article
Full-text available
This systematic study deals with the influence of deep cryogenic treatment (DCT) on microstructure and surface properties of austenitic stainless steel AISI 304 L on different length scales and in the surface region. The study incorporates different analysis techniques, such as light microscopy, scanning electron microscopy (SEM), energy dispersive...
Article
The present work reports on cationization characteristics of organic molecules in alkali metal environment. Samples of arginine and polyethylene glycol polymers with average masses of 600, 1000 and 1500 were mixed with sodium- and potassium trifluoroacetate of various concentrations, and analyzed through secondary ion mass spectrometry. Bombardment...
Article
Full-text available
In our study, plasma surface modification was employed to tailor the surface properties of magnesium in terms of surface chemistry, topography, and wettability. For two sets of samples, the plasma treatment involved two steps using two different gases (hydrogen and oxygen), while one set of samples was treated with one step only using oxygen. X-ray...
Article
Full-text available
The influence of H2 flooding on the development of surface roughness during time-of-flight secondary ion mass spectrometry (ToF-SIMS) depth profiling was studied to evaluate the different aspects of a H2 atmosphere in comparison to an ultrahigh vacuum (UHV) environment. Multilayer samples, consisting of different combinations of metal, metal oxide,...
Conference Paper
Full-text available
Forming industry is confronted with ever increasing demands on productivity, quality and performance of tools and dies. The main limiting factors are wear and fatigue resistance. Good abrasive wear resistance is obtained by increasing material hardness, which however may hamper toughness and fatigue resistance. Therefore different surface engineeri...
Article
This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and ag...
Article
Full-text available
This work explores the possibility of depth profiling of inorganic materials with Megaelectron Volt Secondary Ion Mass Spectrometry using low energy primary ions (LE MeV SIMS), specifically 555 keV Cu ²⁺ , while etching the surface with 1 keV Ar ⁺ ions. This is demonstrated on a dual-layer sample consisting of 50 nm Cr layer deposited on 150 nm In...
Conference Paper
The influence of the flooding gas during ToF-SIMS depth profiling was studied to reduce the matrix effect and improve the quality of the depth profiles. The profiles were measured on three multilayered samples prepared by PVD. They were composed of metal, metal oxide, and alloy layers. Thickness of the layers for different samples was between 3 and...
Conference Paper
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a very versatile surface-sensitive mass spectrometry method regarding the type of data that can be acquired. Measuring mass survey spectra, we analyse the sample surface and determine different ions through their m/z values as well as their intensities. SIMS depth profiles offer us the po...
Article
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Nanoporous ceramic coatings such as titania are promoted to produce drug-free cardiovascular stents with a low risk of in-stent restenosis (ISR) because of their selectivity towards vascular cell proliferation. The brittle coatings applied on stents are prone to cracking because they are subjected to plastic deformation during implantation. This st...
Article
Natural clinoptilolite (CLI) exhibited a high efficacy in ciprofloxacin (CIP) removal from aqueous solution by adsorption. However, the regeneration of the spent adsorbent was a challenge since the adsorption occurred via electrostatic interactions and ion-exchange reaction. Herein, the feasibility of non-thermal plasma (NTP) was studied for the re...
Article
Full-text available
Human hair absorbs numerous biomolecules from the body during its growth. This can act as a fingerprint to determine substance intake of an individual, which can be useful in forensic studies. The cocaine concentration profile along the growth axis of hair indicates the time evolution of the metabolic incorporation of cocaine usage. It could be eit...
Article
V2O5–WO3, supported on TiO2 catalyst, was tested for n-butane oxidative dehydrogenation with NO/O2. The effect of physical oxygen mobility and nature in the V2O5–WO3/TiO2 catalyst on applicative catalytic performance was investigated. The influence of the O2/NO species on chemical reaction products/Mars–van Krevelen (MvK) cycle was examined by doin...
Article
The measured Auger electron spectroscopy (AES) depth profiles of the as-deposited Ag/Ni multilayers demonstrate a strong preferential sputtering effect. In the framework of the Mixing-Roughness-Information depth (MRI) model, the influence of preferential sputtering on the “measured” depth profile is quantitatively evaluated. The mass conservation u...
Article
Energy-efficient photocatalytic CO2 reduction (PCO2R) into sustainable solar fuels is a highly enticing challenge for simultaneous settling of energy and environmental issues. Herein, we illustrate the synthesis and photocatalytic performance of a judiciously designed plasmonic Au nanoparticles photodeposited on TiO2-decorated N-doped graphene (ANG...
Article
The selection of the wood surface pre-treatment process prior to finishing for an optimal wood-coating relationship can be challenging, but has a great significance for the properties of the coated products. The present study compares the surface properties of beech (Fagus sylvatica L.) wood after mechanical (MT), physical (PT) and chemical (CT) tr...
Article
Full-text available
The influence of the flooding gas during ToF-SIMS depth profiling was studied to reduce the matrix effect and improve the quality of the depth profiles. The profiles were measured on three multilayered samples prepared by PVD. They were composed of metal, metal oxide, and alloy layers. Dual-beam depth profiling was performed with 1 keV Cs⁺ and 1 ke...
Article
Potential induced degradation (PID) is a solar cell related degradation mechanism due to high potential difference in a photovoltaic (PV) module between the solar cells and its grounded frame. This type of degradation is well known for silicon PV, however, for perovskites it has not been thoroughly researched yet. Here, we investigate the PID of pe...
Article
Composites of TiO2 and different amounts of plasmonic noble metal Au (0.25-2 wt.%) were synthesized by employing the wet impregnation technique. The results of SEM, TEM, XRD and N2 physisorption analyses reveal that the morphologies of the prepared composites are similar to the morphology of bare TiO2 support and are not influenced by the increasin...
Article
Thin polymer films were deposited on polished stainless-steel samples by PECVD from a cyclopropylamine precursor and characterized by X-ray photoelectron spectroscopy, secondary-ion mass spectrometry and glow-discharge optical emission spectroscopy (GDOES) depth profiling. These depth profiles exhibited reasonable agreement. The GDOES involved the...
Article
Laser texturing is a process that alters material's surface properties by modifying its morphology, which can improve properties like adherence, wettability, thermal and electrical conductivity and friction. Here, the effect of laser texturing was studied on Ti6Al4V biomedical material. In this research, two types of patterned surfaces: crosshatch...
Article
Full-text available
Nanostructured Fe2TiO5 (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe2TiO5 with high crystallinity and a large specific surface area. Herein, Fe2TiO5 nanofibers were sy...
Conference Paper
The influence of the flooding gas and water during the ToF-SIMS depth profiling was studied in order to reduce the matrix effect and improve the quality of depth profiles. ToF-SIMS depth profiles were measured on three multilayered samples prepared by PVD deposition and on the PET foil. Multilayered samples were composed of metal, metal oxide and a...
Article
Layer-by-layer bioactive coatings on AISI 316LVM and Ti90Al6V4 alloy were developed, showing great promise for biomedicine, especially as part of implantable metal-based composites. A corrosion study of the coated and uncoated samples was performed using electrochemistry. It was proven that such coatings do not increase the corrosion susceptibility...
Article
Styrene is a widely used monomer in polymer industries for the manufacturing of plastics, rubbers and resins. The commercial styrene production process suffers from disadvantages such as requiring multiple steps, catalyst deactivation, high energy consumption and low yield. To address the aforementioned problems, metal complex catalysed single-step...
Article
Full-text available
Nanocrystalline nickel manganite (NiMn2O4) powder with a pure cubic spinel phase structure was synthesized via sol-gel combustion and characterized with XRD, FT-IR, XPS and SEM. The powder was mixed with sodium alginate gel to form a nano-biocomposite gel, dried at room temperature to form a thick film and characterized with FT-IR and SEM. DC resis...
Article
Full-text available
Titanium foils of different thicknesses were anodized, and the photocatalytic activity of the resulting TiO2 nanotube (NT) layers was determined. All of the titanium foils were anodized simultaneously under identical experimental conditions to avoid the influence of the aging of the anodizing electrolyte and other anodization parameters, such as vo...
Article
Full-text available
WnO3n−1 nanotiles, with multiple stoichiometries within one nanotile, were synthesized via the chemical vapour transport method. They grow along the [010] crystallographic axis, with the thickness ranging from a few tens to a few hundreds of nm, with the lateral size up to several µm. Distinct surface corrugations, up to a few 10 nm deep appear dur...
Article
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The sol-gel synthesis process is a versatile method used to produce a wide diversity of materials and is being increasingly used as a surface modification method to alter porosity, wettability, catalytic activity, biocompatibility and corrosion performance of underlying substrates. Silane sol–gel films deposited on aluminium and aluminium alloys ha...
Article
Full-text available
Enzymatic polymerization of lignin can generate a variety of value-added products concomitantly replacing fossil-based resources. In line with this approach, a laccase from the thermophilic fungus Myceliophthora thermophila (MtL) was used to couple a hydrophobicity enhancing fluorophenol (FP) molecule, namely 4-[4-(trifluoromethyl)phenoxy]phenol (4...
Article
Full-text available
Cellulose is a promising biomass material suitable for high volume applications. Its potential lies in sustainability, which is becoming one of the leading trends in industry. However, there are certain drawbacks of cellulose materials which limit their use, especially their high wettability and low barrier properties, which can be overcome by appl...
Article
Full-text available
Herein, we demonstrated a highly sensitive and ultra-fast photodetector based on nano-CdS thin film synthesized via spray pyrolysis technique. The effect of variations in molar concentration of the sulfur ion sources (thiourea) on the structural and optical properties of the CdS thin films was investigated. The XRD patterns illustrate the hexagonal...
Article
The influence of deposition and annealing parameters on optical, structural and photocatalytic properties of N-doped titanium-dioxide (TiO 2 ) thin films have been studied. Anatase and anatase-rutile crystalline phase mixture TiO 2 thin films were obtained depending on the reactive direct current (DC) sputtering and annealing conditions. Deposition...
Article
The decomposition of NH3 over Cu–Zn catalysts, supported on ceria and titania, was investigated, producing carbon (di)oxide-free H2. The rate of the H2 formation at the exposed metallic Cu atoms (cumulative turnover frequency) for dispersed Cu–Zn depended strongly on the type of metal oxide support, indicating that the pathway active sites of Cu–Zn...
Article
Transition metal carbides and nitrides with large surface areas are attractive for various catalytic reactions. The synthesis of molybdenum carbide, molybdenum nitride and nanocomposite mixed-phase nanowires with the preserved structural morphology of two different precursor reactant materials by heating in diverse gas mixtures is reported herein....
Article
Full-text available
In this work, we evaluated the effect of the counter-body material (the same or dissimilar) and contact configuration (moving or stationary body), at similar contact tribological conditions, on the tribochemical and nanotopography characteristics of adsorbed surface films. Zinc dialkyldithiophosphate (ZDDP), the best performing anti-wear additive,...
Article
Composites of different TiO2 supports (anatase nanoparticles (TNP) and nanorods (TNR)) and 1 wt% of Au were synthesized upon wet impregnation preparation procedure. The size of formed Au ensembles in the composites was influenced by the difference in the zeta potential value (pHPZC) of TiO2 supports. The positive surface charge of TNR nanorods duri...
Article
Full-text available
In the process of wood bonding, the usage of aged and inactivated wooden elements can cause a reduction in mechanical properties of products containing wood-adhesive joints. Treating wood with an atmospheric air plasma represents a sophisticated technique for surface activation. With this regard, to enhance the bondability of normal beech wood ( Fa...
Article
Full-text available
The article “Enhancement of strength of adhesive bond between wood and metal using atmospheric plasma treatment” written by Jure Žigon, Janez Kovač, Rok Zaplotnik, Jaša Saražin, Milan Šernek, Marko Petrič and Sebastian Dahle, was originally published Online First without Open Access.
Article
In recent years polyoxometalates (POMs) have attracted significant research interest due to versatile properties. These properties are determined by the size, structure and elemental composition of POMs and hence play an important role in their application. In the present study, the ion beam irradiation (10 keV C⁺ ions, 5×10¹⁴-2.5×10¹⁵ ions/cm²) ha...
Article
The mechanism of Cu2+ loading into commercially available natural HEU‐type and synthetic LTA‐type zeolites for their possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis, SEM/EDXS, XRD, XAS and XPS analyses revealed 4‐fold coordination of Cu2+ cations with oxygen atoms in the pores,...
Article
The low energy range (a few 100 keV to a few megaelectronvolts) primary ion mode in MeV secondary ion mass spectrometry (MeV SIMS) and its potential in exploiting the capabilities of conventional (keV) SIMS and MeV SIMS simultaneously were investigated. The aim is to see if in this energy range of both types of materials, inorganic and organic, can...
Article
Full-text available
The purpose of this study is to provide a systematic, complementary research of deep cryogenically treated (DCT) steels AISI M2, M3:2 and M35 including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and X-ray photoelectron spectroscopy (XPS). The DCT effect on selected steels...
Article
Full-text available
Unambiguous evidence is presented that the chloride ions play a dual role in the formation of a micrometre thick film of polymerized [Cu-Cl-MBI] n . This occurs when the copper is exposed to 3 wt.% NaCl solution containing 1 mM of mixture of inhibitors 2-mercaptobenzimidazole, MBI, and octylphosphonic acid, OPA, in the molar ratio MBI:OPA of 9:1. T...
Article
Full-text available
The heat treatment of dental alloys prior to porcelain application/veneering has been proposed as a way to ensure sufficient oxide scale and to promote the porcelain’s adherence in porcelain-fused-to-metal (PFM) fixed dental prostheses. The present study investigates the relationship between the bond strength of the dental porcelain to selective-la...
Article
Full-text available
Ionizing radiation has been identified as an option for sterilization of disposable filtering facepiece respirators in situations where the production of the respirators cannot keep up with demand. Gamma radiation and high energy electrons penetrate deeply into the material and can be used to sterilize large batches of masks within a short time per...
Article
The third generation of concentrating solar power (CSP) hybrid absorbers with enhanced solar absorptance and low thermal emittance (spectrally selective) is designed to have a high solar-to-thermal energy conversion efficiency, in spite of robust, long-term resistance to environmental loads. In this study, we report on the deposition, testing, and...
Article
Cover Picture: The study demonstrates complete removal of aflatoxin B1 from the artificially contaminated corn kernels with an indirect cold atmospheric pressure plasma treatment generated with a surface barrier discharge system working in the ambient air. Furthermore, it presents the first step towards acceptance of plasma technology as a safe foo...
Article
Full-text available
The development of affordable, low-iridium-loading, scalable, active, and stable catalysts for the oxygen-evolution reaction (OER) is a requirement for the commercialization of proton-exchange membrane water electrolyzers (PEMWEs). However, the synthesis of high-performance OER catalysts with minimal use of the rare and expensive element Ir is very...
Article
Full-text available
Ultrafast laser processing with the formation of periodic surface nanostructures on the 15×(Ti/Zr)/Si multilayers is studied in order to the improve cell response. A novel nanocomposite structure in the form of 15×(Ti/Zr)/Si multilayer thin films, with satisfying mechanical properties and moderate biocompatibility, was deposited by ion sputtering o...
Article
Full-text available
Defluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H2 plasma sustained in the E- and H-modes at various powers, pressures and treatment time...
Conference Paper
Secondary ion mass spectrometry (SIMS), most often combined with time of flight (ToF) analysis, is a type of surface sensitive mass spectrometry method. It works by bombardment of analysed surface with primary ions in a high vacuum ambient. Primary ion impacts cause sputtering of neutral and charged species. The latter are extracted into the analys...
Article
Full-text available
This study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultralow loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth o...
Article
Liquid tin samples at a temperature of 250 °C were exposed to neutral deuterium atoms at a flux of about 10 ²⁴ m ⁻² s ⁻¹ . The source of deuterium (D) atoms was the flowing afterglow of a low-pressure deuterium plasma sustained with a microwave discharge in the surfatron mode. The samples were analyzed by thermal desorption spectroscopy and time of...
Article
Depth profiles of a Ni/Ag multilayer with 25 nm nominal layer thickness obtained by Time-of-Flight Secondary Mass Spectrometry (ToF-SIMS) show the usual rounded top shape of the Ni layers, but a strange profile of Ag with two peaks of different intensities. Application of the Mixing-Roughness-Information depth (MRI)-model for quantification of both...
Article
Full-text available
Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5‐day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation...
Article
Mycotoxins, the toxic secondary metabolites produced by filamentous fungi, are found in up to 80% of global food and feed crops. Here, we report on the complete removal of aflatoxin B 1 (AFB 1) from the artificially contaminated corn kernels with an indirect cold atmospheric pressure plasma (CAP) treatment generated with a surface barrier discharge...